Week 7

Question 1

Monogenic disease (2 points)

Answer 1

Simple Mendellian inheritance, single locus.

Question 2

Polygenic

Answer 2

Different alleles at multiple independent genes, influenced by environmental factors

Question 3

Position-Independent Cloning Strategy example

Answer 3

For Haemophilia A they knew which factor was missing (factor VIII), obtained their aminoacid sequence, reverse translated and found a Factor VIII clone in the gene library. Then can be re-probed.

Question 4

Positional cloning strategy basics

Answer 4

Clone DNA in candidate region and mutation screen. Test candidate gene in affected people.

e.g. cystic fibrosis, 2 genes in chromosome 7.

Question 5

Why is gene mapping possible due to recombination? basics

Answer 5

Polymorphisms close are inherited together and allows differentiation between chromosomes. If all polymorphisms around area A, then disease probably associated with that area.

Question 6

Multifactorial Diseases are determined by(3)

Answer 6

• more than 1 gene
• Penetrance (not all individuals have show the trait)
• Expressivity (all have trait, but not to the same degree)

Question 7

How are ways of studying complex traits? (4)

Answer 7

• Compare adopted individuals (same environment, different genes)
• Twin studies (monozygotes vs dizygotes, monozygotes raised apart)
• Linkage studies
• GWAS

Question 8

Major personalised genetic testing (4)

Answer 8

• Pharmacogenics (how medication reacts to individual’s genetic makeup)
• Genetic predisposition testing
• Ancestry
• Nutrigenomics

Question 9

Goal of transcriptional fusion?

Answer 9

Make an RNA transcript

Question 10

Goal of translation fusion

Answer 10

Make RNA and protein (hybrid)

Question 11

What should be considered when choosing/making a promoter? (3)

Answer 11

• Strength
• Regulation (inducible or repressible?)
• Specificity (at host level? at tissue level)

Question 12

Eukaryotic promoters components (4)

Answer 12

• GC box (100 bps, where transcription factors bind)
• CAAT box (80 bps)
• TATA box (core promoter)
• CAP site (where transcription start. Leader region (5’) right after)

Question 13

Prokaryotic promoters components (3)

Answer 13

• TATA box
• TTGACA
• Direction changes activity

Question 14

Why are native promoters often better?

Answer 14

Best expression for specific gene and correct localisation.

Question 15

What are constitutive promoters?

Answer 15

Key genes constantly active expressed equally across all cell types. Independent of environment and species.

Question 16

How does the Lambda Repressor Switch works? (4)

Answer 16

3 promoters controlling 2 genes and repressor. Lysogenic: inhibitor only active, DNA integrates. Lytic: inhibitor inactive, replication and lysis.

Question 17

T7 promoter as a strong regulatable promoter. (5)

Answer 17

Very active, not good for toxic products, has 1 hours lag, is inducible and native host system is not ideal.

Question 18

GAL regulation

Answer 18

• GAL4 is transcription factor
• Combines with GAL80, sitting on promoter and preventing expression
• GAL3 dislodges that complex when galactose is present.

Question 19

Translational fusion

Answer 19

Fusion of protein+protein or protein+tag. Need to know coding region to put within same reading frame.

Question 20

What are affinity tags?

Answer 20

Facilitate protein purification via affinity chromatography

Question 21

GST gene fusion vectors (2)

Answer 21

• Very strong

- What is wanted (often tags) will bind to glutathione

Question 22

Histidine basics

Answer 22

• Activity will lyse cells, protein then purified, in electrophoresis produces single band ideally.